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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org,
	Andy Lutomirski <luto@amacapital.net>,
	Josh Triplett <josh@joshtriplett.org>,
	Haitao Huang <haitao.huang@linux.intel.com>,
	Jethro Beekman <jethro@fortanix.com>,
	"Dr . Greg Wettstein" <greg@enjellic.com>
Subject: [RFC PATCH v5 4/5] x86/traps: Attempt to fixup exceptions in vDSO before signaling
Date: Fri, 14 Dec 2018 13:57:28 -0800	[thread overview]
Message-ID: <20181214215729.4221-5-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20181214215729.4221-1-sean.j.christopherson@intel.com>

Call fixup_vdso_exception() in all trap flows that generate signals to
userspace immediately prior to generating any such signal.  If the
exception is fixed, return cleanly and do not generate a signal.

The goal of vDSO fixup is not to fixup all faults, nor is it to avoid
all signals, but rather to report faults directly to userspace when the
fault would otherwise directly result in a signal being sent to the
process.

Suggested-by: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/traps.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 9b7c4ca8f0a7..b1ca05efb15e 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -61,6 +61,7 @@
 #include <asm/mpx.h>
 #include <asm/vm86.h>
 #include <asm/umip.h>
+#include <asm/vdso.h>
 
 #ifdef CONFIG_X86_64
 #include <asm/x86_init.h>
@@ -209,6 +210,9 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, const char *str,
 		tsk->thread.error_code = error_code;
 		tsk->thread.trap_nr = trapnr;
 		die(str, regs, error_code);
+	} else {
+		if (fixup_vdso_exception(regs, trapnr, error_code, 0))
+			return 0;
 	}
 
 	/*
@@ -560,6 +564,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
 		return;
 	}
 
+	if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0))
+		return;
+
 	tsk->thread.error_code = error_code;
 	tsk->thread.trap_nr = X86_TRAP_GP;
 
@@ -774,6 +781,10 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
 							SIGTRAP) == NOTIFY_STOP)
 		goto exit;
 
+	if (user_mode(regs) &&
+	    fixup_vdso_exception(regs, X86_TRAP_DB, error_code, 0))
+		goto exit;
+
 	/*
 	 * Let others (NMI) know that the debug stack is in use
 	 * as we may switch to the interrupt stack.
@@ -854,6 +865,9 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	if (!si_code)
 		return;
 
+	if (fixup_vdso_exception(regs, trapnr, error_code, 0))
+		return;
+
 	force_sig_fault(SIGFPE, si_code,
 			(void __user *)uprobe_get_trap_addr(regs), task);
 }
-- 
2.19.2


  parent reply	other threads:[~2018-12-14 21:57 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-14 21:57 [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 1/5] x86/vdso: Add support for exception fixup in vDSO functions Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 2/5] x86/fault: Add helper function to sanitize error code Sean Christopherson
2018-12-14 21:57 ` [RFC PATCH v5 3/5] x86/fault: Attempt to fixup unhandled #PF on ENCLU before signaling Sean Christopherson
2018-12-14 21:57 ` Sean Christopherson [this message]
2018-12-14 21:57 ` [RFC PATCH v5 5/5] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Sean Christopherson
2018-12-19  9:21   ` Jarkko Sakkinen
2018-12-18  4:18 ` [RFC PATCH v5 0/5] x86: Add vDSO exception fixup for SGX Jarkko Sakkinen
2018-12-18 15:08   ` Sean Christopherson
2018-12-19  4:43     ` Jarkko Sakkinen
2018-12-19  5:03       ` Jarkko Sakkinen
2018-12-19  7:58 ` x86/sgx: uapi change proposal Jarkko Sakkinen
2018-12-19  8:41   ` Jethro Beekman
2018-12-19  9:11     ` Jarkko Sakkinen
2018-12-19  9:36       ` Jethro Beekman
2018-12-19 10:43         ` Jarkko Sakkinen
2018-12-19 14:45         ` Sean Christopherson
2018-12-20  2:58           ` Andy Lutomirski
2018-12-20 10:32             ` Jarkko Sakkinen
2018-12-20 13:12               ` Jarkko Sakkinen
2018-12-20 13:19                 ` Jarkko Sakkinen
2018-12-22  8:16               ` Jarkko Sakkinen
     [not found]                 ` <20181222082502.GA13275@linux.intel.com>
2018-12-23 12:52                   ` Jarkko Sakkinen
2018-12-23 20:42                     ` Andy Lutomirski
2018-12-24 11:52                       ` Jarkko Sakkinen
2019-01-02 20:47                   ` Sean Christopherson
2019-01-03 15:02                     ` Jarkko Sakkinen
     [not found]                       ` <20190103162634.GA8610@linux.intel.com>
2019-01-09 14:45                         ` Jarkko Sakkinen
2018-12-21 16:28             ` Sean Christopherson
2018-12-21 17:12               ` Andy Lutomirski
2018-12-21 18:24                 ` Sean Christopherson
2018-12-21 23:41                   ` Jarkko Sakkinen
2018-12-23 20:41                   ` Andy Lutomirski
2018-12-24 12:01                     ` Jarkko Sakkinen
2018-12-21 23:37                 ` Jarkko Sakkinen
2018-12-22  6:32                 ` Jarkko Sakkinen
2019-01-08 19:27               ` Huang, Kai
2019-01-08 22:09                 ` Sean Christopherson
2019-01-08 22:54                   ` Andy Lutomirski
2019-01-09 16:31                     ` Sean Christopherson
2019-01-10 21:34                       ` Andy Lutomirski
2019-01-10 22:22                         ` Huang, Kai
2019-01-10 23:54                         ` Sean Christopherson
2019-01-11  0:30                           ` Andy Lutomirski
2019-01-11  1:32                             ` Sean Christopherson
2019-01-11 12:58                       ` Jarkko Sakkinen
2019-01-11 13:00                         ` Jarkko Sakkinen
2019-01-11 23:19                         ` Sean Christopherson
2019-01-18 14:37                           ` Jarkko Sakkinen
2019-01-10 17:45                     ` Jarkko Sakkinen
2019-01-10 21:36                       ` Andy Lutomirski
2019-01-11 16:07                         ` Jarkko Sakkinen
2019-01-09  5:24                   ` Huang, Kai
2019-01-09 17:16                     ` Sean Christopherson
2019-01-10  0:21                       ` Huang, Kai
2019-01-10  0:40                         ` Sean Christopherson
2019-01-10 17:43                 ` Jarkko Sakkinen
2018-12-20 10:30           ` Jarkko Sakkinen
2018-12-19 14:43     ` Dr. Greg
2018-12-20 10:34       ` Jarkko Sakkinen
2018-12-20 22:06         ` Dr. Greg
2018-12-21 13:48           ` Jarkko Sakkinen
2018-12-20 12:08     ` Arnd Bergmann
2018-12-20 12:49       ` Jarkko Sakkinen

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